The universe's galaxies are the nurseries of stars, and in one known case life, and come in an impressive range of shapes and sizes. But only recently has it become possible to simulate how that diversity came about.

Lenticular galaxies boast a disc, like spiral galaxies, but they also share properties with elliptical galaxies, since they are usually low in dust and gas and don't tend to have obvious spiral arms. They are named for their lens-like shapes when seen along their edges.

Theorists are divided over how lenticular galaxies lost their gas in the first place – some think they used it up to form stars, while others believe it was stripped away as the galaxies passed through hot gas in galaxy clusters.

Some lenticular galaxies have retained a little gas, though. The gas in NGC 5866 is thought to be coupled to a thin lane of dust, seen as a long, dark bar. In 2006, Hubble spotted wisps of dust emanating from both sides of this dust lane. The wisps may have been created by young massive stars, which stir up the gas and dust around them. The observation suggests that the galaxy continues to form some stars, although not enough to form spiral arms. (Image: NASA/ESA/Hubble Heritage Team/STScI/AURA)